Based on intelligence indicating that Al Qaeda and associated movements continue to express interest in attacking U.S. mass transit systems, the Government Accountability Office (GAO) has issued a redacted version of a classified report on “explosives detection technologies [that] are available or in development that could help secure passenger rail systems.” However, GAO noted that “while these technologies show promise in certain environments, their potential limitations in the rail environment need to be considered and their use tailored to individual rail systems.” In its report, Explosives Detection Technologies to Protect Passenger Rail, GAO did not make any specific recommendations, but it did raise “various policy considerations.” The report pointed to the fact that the TSA and passenger rail operators share the responsibility for security, which is said could complicate decisions. In addition, the GAO recommended the use of risk-management principles to guide decision-making related to technology and resource allocation.

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